Drying Methods

In choosing appropriate drying methods, consider the number of items, the value, their frequency of use, and time constraints. More than one method may be appropriate. In some cases, the cost of replacement may be less than recovery, or it may be possible to request photocopies from other libraries. In other cases, it may be better to accept the loss.

Freezer Drying

See Blast Freezing, FREEZING METHODS pg 37

Vacuum Freeze-Drying

See FREEZING METHODS, pg 37

Vacuum Drying or Vacuum Thermal Drying

Less expensive alternative to vacuum freeze drying. Easier than air drying and more cost effective for large numbers of materials.

A vacuum is used to pull water out of the drying chamber, then warm dry air is pumped in to complete the drying. Most of the water passes through a liquid state before vaporizing and may cause further damage such as feathering of inks and physical distortion. Rebinding or recasing may be necessary. Books with coated papers will block.

Air Drying

Good choice when number and value of damaged items does not warrant expensive methods, although it does require large amounts of space, it is labor intensive and may result in much physical distortion of books.

Stand frozen or wet books upright in a ventilated room. As the pages open naturally, interleave them with absorbent paper (white, blank, e.g., newsprint or paper towels) which must be changed frequently. Do not interleave too much or the spine of the book will warp; do not exceed 1/3 of the book's thickness. The volume may be hung to finish drying on three or more lines of monofilament fishing line. Do not hang books that are saturated with water or that weight more than 6lbs. heavy or saturated books stand upright on head end and air-dried with front edges supported. Books with coated paper need special care such as frequent fanning of the pages to ensure that the pages do not stick together, but this method may still lead to blocking of coated papers.

Sheet material can be separated by the Waters technique then laid out on clean white blotting paper or unprinted newsprint.

Dehumidification

Large commercial dehumidifiers are brought into the facility with all collections and equipment left in place. Temperature and humidity are carefully controlled until all is dried. Since materials do not need to be moved, this process saves transport time and costs.